Any of you who use gas checks on your cast bullets know they are not exactly cheap anymore, they kind of rise and fall with the price of copper. Well, I was on Ebay this evening, and noticed somebody has aluminum gas checks for sale. I'm somewhat leery of new products I've never heard of. Any of you have experience with these, and if so what did you think of them? Are they well made, and do they stay on the bullets as well as copper ones?